What is light? Light is that part of the electromagnetic spectrum, that is seen by your naked eyes. In order for you to understand lighting, I am going to lead you through the basics of light, that is its terminology.
Why the basics.
I have decided to talk about the basics of light because I feel it will help you to understand how light is illuminated.
In the first step, I will walk you through the basic lighting terminology that will help you understand and appreciate the light.As I walk you through the basics of lighting, I will define the basic terms used in lighting.
Basic lighting terminology
Here are the basic lighting terms for you.
- Luminous efficacy
- Luminous flux
- Light intensity
Luminous flux describes the total light power emitted by a light source
Luminous efficacy describes the efficacy of a lamp. It is expressed as a ratio of the luminous flux in the lumen and the power used in watts.
An ideal light source radiates its luminous flux evenly, in all directions in a room. With its light intensity being equal in all directions. But in practice, this is not so because of the uneven spatial distribution of luminous flux. This is mainly attributed to either lamp design or the manner in which the luminous is formed.
This is the unit of light intensity,as well as a basic unit of lighting engineering from which all other lighting engineering values are derived.
This is a measure of luminous flux density on a surface. Illuminance is expressed as a ratio of luminous flux incident on a surface to the size of the flux.
Colour of light
This is the color of the light emitted by a lamp. At this point, it is good to mention that the color of light is categorized into three main groups.
1.Warm white range
2. Neutral white range
3.Daylight white range
Warm white range.
This is the color range with the coolest temperature below 4000k
Neutral white range
The neutral range color has a temperature range between 4000k and 5000k
Daylight white range
The lamps in this have a temperature range above 5000k
I know you may be asking as to what is color rending. I know you have been to places,where when the light bulbs are switched on, the color of the clothes that you are wearing might seem to have changed. This experience is the effect of color rending. Simply put, color rending is the ability of a light source to reproduce the surface colors.
Having shown you some of the basic terminology used in lighting,I would like to take you through the type of lamps available on the market.
Types of Lamps
It is important to note that the lamps that I am talking about, are those lamps that use electricity to produce light. Electric light sources are divided into three main categories. This grouping is based on how a particular lamp converts electricity into light. Basically, these categories are
- Thermal radiator
- Discharge lamps
- Semi-conductors or LED
Electric lamps in this group,produce light using an incandescent metal filament. This is a process whereby as the temperature increases, the light spectrum of the filament shifts from a red heat to warm white light.
Projected features of thermal radiators
- Low color temperature
- Excellent color rendition
- Good as a point light source
- High luminous which results in its brilliance
- Incandescent are excellent dimmers
- Do not require additional feature or equipment for starting
- They have a low life span
Operation of thermal radiators
In general, it’s good for you to know that all thermal radiators are incandescent lamps. Their basic operation is such that an electric current causes the filament to glow. As the temperature of the light spectrum shifts from a red heat to warm white light.
When you dime incandescent lamps, the warm white temperature shits to the red heat of the filament. Incandescent lamps generate more thermal radiation than visible light.
Practical lamps that are thermal radiators
The lamps listed below are practical thermal radiators.
- Incandescent lamps
- Tungsten lamps
- Halogen lamps
Lamps in this group generate light either through photo-luminescence or electro-luminescence. This entails that light is generated using either chemical or electrical processes. Discharge lamps can be divided into low-pressure and high-pressure lamps.
Below is a list of discharge lamps.
- Fluorescent lamp
- Compact fluorescent lamp
- Metal vapour lamp
- High-pressure sodium vapour lamp.
Fluorescent lamps are low-pressure discharge lamps. In this lamp, light is emitted from a large surface,and its light is of diffuse-type with low brilliance.
Operation of fluorescent lamps.
For a fluorescent to operate, it needs to have
- Fluorescent coating.
You may be wondering as to how these items or features produce light in fluorescent lamps. Here is how the electrode produces or releases electrons that collide with mercury atoms. As a result, of this collision the mercury atoms become excited, consequently emitting UV radiation. This UV radiation is converted into visible light by the fluorescence coating. A voltage is used to ignite the lamp.
Properties of a fluorescent lamp.
Fluorescent lamps light colors are
- Warm white
- Neutral white
- Daylight white
For a fluorescent lamp to operate, it needs a ballast and a starter.
Fluorescent lamps consume less power and they have a longer life span.
Compact fluorescent lamps
Compact fluorescent lamps are low-pressure discharge lamps. The operating principle of compact fluorescent lamps is the same as that of an ordinary fluorescent lamp.
Properties of compact fluorescent lamps
- They have a high luminous efficacy
- They have a long life span
- They are shorter in length than ordinary fluorescent lamps,as a result,they can produce focused light.
- Compact fluorescent lamps with integrated starters can not be dimmed.
- Compact fluorescent lamps are available as straight tubes as well as twisted tubes.
Metal vapor lamps
what are metal vapor lamps? These are lamps that produce light by an electric arc in a gaseous mixture of vaporized mercury and metal halide. (I know you may be wondering as to what are metal halides, well these are compounds between metals and halogens)The addition of metal halides radiates more light and improves color.
Properties of metal vapour lamps
- Metal vapour lamps have excellent colour rendition.
- They have a good luminous efficacy
- They have a long life span.
Semi-conductor or LED lamps.
You may be wondering as to what are semi-conductors, these are simply engineering materials that are neither conductors nor insulators. They naturally fall in between conductors and insulators.semiconductors are said to act as insulators at room temperature or temperature below room temperature. As you increase the temperature of semiconductors above room temperature, their resistance decreases with the increase in temperature until at a certain temperature a semiconductor material becomes a conductor.
Semiconductors were originally used in electronics circuits as indicator lamps. In recent years, they have been used in general lighting applications were incandescent and fluorescent lamps have been employed.
Learn more on the benefits of using LED lights here
Characteristics of LED lamps.
LED is a short term for light-emitting diode when you see LED you to know that it is just a diode, only that it’s a special diode that can produce light. A diode is made from a semiconductor.
- They do not have filaments, they are made from a cluster of individual LEDs.
- They are instant on lamps
- A new model of LED is dimmable
- They are robust, hence they can take bumps without being damaged
- They have a long or longer life span
- LED lamps to come in all forms of light temperature, that is, warm white. neutral white, day light as well as in multi-colors.
- The LED lamps are not affected by cold weather, on the contrary, their light input is increased. This feature makes led lamps suitable for use in cold storage facilities and refrigerated display cases
- LED lamps are sensitive to heat, this does not put them on the disadvantage, because most LED lamps and fixtures are designed with heat sinks.
- The LED lamps to use 80% less energy than incandescent and halogen lamps
- They use 15% less energy than compact fluorescent lamps.
- when you compare led lamps with other sources of light, the brightness of LED is more than incandescent. This is true when you compare the energy used to produce the brightness of the lamps in lumens LEDs use less energy to produce the same number of lumens as other conventional lamps. All in all LED lamps are excellent energy savers.
- LED lamps do not contain mercury, hence they can be disposed of as normal trash.
- LED lamps cost more than incandescent lamps but their long life span makes them cheaper in the long run.
Should you have any questions or contribution you are free to do so.
Author Themba Mbewe Posted on December 5, 2018